In this study, we reported the forming-free resistive switching behavior in the Ru/RE2O3/TaN (RE = Nd, Dy, and Er) memory devices using thin Nd2O3, Dy2O3, and Er2O3 films fabricated with full room temperature process. The dominant conduction mechanisms of the Ru/RE2O3/TaN devices in the low-resistance state and high-resistance state are Ohmic behavior. The Ru/Dy2O3/TaN memory device exhibited high resistance ratio, nondestructive readout, reliable data retention, and good endurance. Ru/Dy2O3/TaN memory device has a great potential for the application in nonvolatile resistive switching memory. (C) 2011 American Institute of Physics. [doi:10.1063/1.3638490]